Rotary valve having bypass state

ABSTRACT

A rotary valve that includes a stator, a rotor and a plurality of sample channels. The stator includes a stator surface having an inlet port, an outlet port and a plurality of selectable ports. The rotor includes a rotor surface having a first rotor channel and a second rotor channel. The rotor is configurable in a plurality of rotor positions, each of which couples the inlet port to one of the selectable ports through the first rotor channel and couples the outlet port to another one of the selectable ports through the second rotor channel. The two selectable ports are coupled to each other through one of the sample channels. The rotor has a bypass state defined by a rotor position, or angular range of rotor positions, at which the inlet port is coupled to the outlet port through the second rotor channel.

RELATED APPLICATION

This application claims the benefit of the earlier filing date of U.S.Provisional Patent Application Ser. No. 63/141,768 filed Jan. 26, 2021and titled “Rotary Valve Having Bypass State,” the entirety of which isincorporated herein by reference.

FIELD OF THE INVENTION

The technology generally relates to devices having microfluidic channelsand rotary valves used to switch between the channels. Morespecifically, the technology relates to a valve that can be used, forexample, with multiple sample channel devices in a liquid chromatographysystem.

BACKGROUND

Liquid chromatography systems often include multiple valves coupled toeach other with tubes to achieve a desired fluidic path configuration. Alarge number of tubes may be connected between the valves to establishthe desired fluidic path configuration. The connections required toconnect the tubing can have unswept volumes that may result in carryoverand poor peak shape. Moreover, the large number of connections increasesthe chance of leakage, system contamination, and significant time istypically required to manually install the tubing and complete theconnections.

Each tube has a volume that can vary substantially from the desired tubevolume due to the large physical tolerance for the inner diameter (ID)of the tube. Thus, the chromatographic results obtained with onechromatographic system may differ markedly from the results obtainedwith a similar chromatographic system due to the differences in the tubevolumes according to the ID manufacturing tolerances. For example, avalve configuration may be used to acquire segments of a first liquidchromatography system for introduction into a second dimensionchromatography system. Alternatively, valves may be configured toconsecutively sample different volumes of the same sample into differentsample loops. Use of this configuration allows a smaller volume ofacquired sample to be used if it is determined that an initial samplevolume results in high mass loading and/or detector saturation problems.In another alternative, complex valve configurations may be used toprovide an identical sample to different single-dimension chromatographysystems to acquire more information about the sample than can beacquired from a single chromatography system. Each of the above valveconfigurations can be adversely affected by the variation in tubevolumes and large number of tube connections that can leak and requiresignificant system installation time.

In some implementations, it is desirable to provide a means to bypasssample channels, or sample loops, used to store volumes of sample. Onemeans is to use what otherwise would be a sample channel as a bypasschannel such that fluid received at the input port of a rotary valve isrouted via the bypass channel to the output port of the rotary valve;however, such operation limits the number of channels available forstoring sample.

SUMMARY

In one aspect, a rotary valve includes a stator, a plurality of samplechannels and a rotor. The stator includes a stator surface having aninlet port, an outlet port, a plurality of selectable ports. Each samplechannel couples one of the selectable ports to another one of theselectable ports. The rotor includes a rotor surface in abutment withthe stator surface. The rotor surface has a first rotor channel and asecond rotor channel defined therein. The rotor has a plurality of rotorpositions at which the first rotor channel couples the inlet port to oneof the selectable ports at one end of one of the sample channels and thesecond rotor channel couples the outlet port to another one of theselectable ports that is at an opposite end of the one of the samplechannels. The rotor has a bypass rotor position at which the inlet portis coupled to the outlet port through the second rotor channel and thefirst rotor channel is not coupled to the inlet port, the outlet port orthe selectable ports.

For each sample channel, the selectable ports coupled at the end of eachsample channel may be diametrically opposite to each other on the statorsurface with respect to a rotor rotation axis and may be disposed atequally spaced angular positions with respect to the rotor rotationaxis.

The bypass rotor position may be defined within an angular range withrespect to a rotor rotation axis. The outlet port may be disposed alonga rotor rotation axis.

The first rotor channel may include an arc portion having a center ofcurvature on a rotor rotation axis.

Each sample channel may include tubing. The stator surface may bedefined on a diffusion-bonded body and the sample channels may bedefined by internal channels in the diffusion-bonded body. The internalchannels may be defined in different layers of the diffusion-bondedbody.

The second rotor channel may define a fluidic path from a rotor rotationaxis to a position on a circle on which the selectable stator ports aredisposed, the circle being concentric with the rotor rotation axis. Thesecond rotor channel may include a plurality of linear portions. Thesecond rotor channel may include an arc portion and a linear portion,wherein the arc portion has a first end at the rotor rotation axis and asecond end, and the linear portion extends from the second end to thecircle.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages of this invention may be betterunderstood by referring to the following description in conjunction withthe accompanying drawings, in which like reference numerals indicatelike elements and features in the various figures. For clarity, notevery element may be labeled in every figure. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIG. 1A is a top view of an embodiment of a stator body.

FIG. 1B is a cutaway side view of the stator body of FIG. 1A.

FIG. 2 is a diagram of a multi-valve array for acquiring samples from achromatography system in a first chromatographic dimension forintroduction into a second chromatography system of a secondchromatographic dimension.

FIG. 3A is a top view of an example of a stator body that can be used aspart of a multi-valve array to replace the multi-valve array of FIG. 2.

FIG. 3B shows the stator body of FIG. 3A; however, the body material isdepicted as transparent so that internal fluid channels are visible.

FIG. 3C is a perspective view of the transparent stator body of FIG. 3Bdepicting the four discrete layers used in the diffusion bonding processto fabricate the stator body.

FIG. 4A is a top view of an example of a stator body that can be used ina multi-valve array for acquiring different volumes of sample for achromatographic injection.

FIG. 4B is a transparent top view of the stator body of FIG. 4A.

FIG. 4C is transparent bottom perspective view of the stator body ofFIG. 4A.

FIG. 4D is an expanded view of the central portion of FIG. 4B

FIG. 5A is a top view of another example of a stator body that that canbe used in a multi-system injector array.

FIG. 5B is a transparent top view of the stator body of FIG. 5A.

FIG. 5C is a transparent bottom perspective view of the stator body ofFIG. 5A.

FIG. 5D is an expanded view of the central portion of FIG. 5B.

FIG. 6A is a top front perspective view of an example of a multi-valvearray.

FIG. 6B is a top perspective back view of the example of a multi-valvearray of FIG. 6A.

FIG. 7 is a mounting assembly for the multi-valve array of FIGS. 6A and6B.

FIG. 8A is a perspective view of an example of a retainer element forthe mounting assembly of FIG. 7.

FIG. 8B is a side view of the retainer element of FIG. 8A.

FIG. 8C is a top view of the retainer element of FIG. 8A.

FIG. 9A is a top cross-sectional view of the right-side portion of thestator body of FIG. 3B.

FIG. 9B is a cross-sectional side view of a portion of the stator bodyshown in FIG. 9A.

FIG. 10A is a cross-sectional side view of a portion of anotherembodiment of a stator body.

FIG. 10B is a top cross-sectional view of a larger portion of the statorbody of FIG. 10A.

FIGS. 11A to 11H are diagrams depicting the configuration of a rotorwith respect to a stator for eight different rotor positions of a rotaryvalve.

FIG. 12 is a magnified view of the ports and rotor channels for FIG.11A.

DETAILED DESCRIPTION

Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure or characteristic describedin connection with the embodiment is included in at least one embodimentof the teaching. References to a particular embodiment within thespecification do not necessarily all refer to the same embodiment.

In brief overview, embodiments disclosed herein are directed to amulti-channel fluidic device, such as a stator array, that includes atleast one stator surface and directed to a mounting assembly for thestator array. Each stator surface is configured to engage and sealagainst a rotor surface of a corresponding rotary valve. Each statorsurface includes stator ports to communicate with rotor ports. In someembodiments, there is at least one fluid channel inside the stator bodythat couples a stator port in one of the stator surfaces (i.e., stator“faces”) with a stator port in another one of the stator surfaces.

The stator array avoids the need to use a large number of tubes toprovide fluidic connections between two or more rotary valves. Instead,stator ports in different stator surfaces are internally coupled to eachother within a single block that includes the stator surfaces for therotary valves. By eliminating most of the tubing connections, the arrayis more robust and leaks and possible contamination points aresignificantly reduced. In addition, chromatographic band dispersion andpeak tailing can be reduced as the volumes associated with tubingconnectors are eliminated. The block can be fabricated from individuallayers of material using a diffusion bonding technique. Use of thestator body reduces the complexity and time required to set up variouschromatographic instrument configurations because most of the fluidicconnections are contained inside the stator array block. The multi-valvearray can be used for a number of applications including, for example,improving loop-to-loop volume accuracy and precision for the collectionof samples for introduction into a second chromatographic dimension.Additionally, the stator array has improved volume characteristics forthe internal sample channels as compared to conventional external sampleloops.

Other embodiments described herein relate to a rotary valve having abypass state. The rotary valve can include multiple sample channelscoupled to its ports. Using a conventional rotary valve, one of thesample channels may be sacrificed to serve as a bypass channel thatallows for fluid to bypass the other channels. Such a bypass channel canadd significant time to operations due to the channel volume. In variousembodiments of the rotary valve described below none of the samplechannels need to be sacrificed and the delay volume, while in bypassmode, is substantially smaller than the delay volume of a samplechannel.

The present teaching will now be described in more detail with referenceto embodiments thereof as shown in the accompanying drawings. While thepresent teaching is described in conjunction with various embodimentsand examples, it is not intended that the present teaching be limited tosuch embodiments. On the contrary, the present teaching encompassesvarious alternatives, modifications and equivalents, as will beappreciated by those of skill in the art. Those of ordinary skill havingaccess to the teaching herein will recognize additional implementations,modifications and embodiments, as well as other fields of use, which arewithin the scope of the present disclosure.

The embodiments described below include the use of a multi-valve arrayin which two or more rotary valves share a stator body (i.e., stator“block”) that includes a stator surface for each valve. For example, therotary valves may be rotary shear seal valves in which each valve has arotor surface that is parallel to and in contact with one of the statorsurfaces. Each rotor surface is configured to rotate about an axis thatis orthogonal to the rotor surface and the corresponding stator surfaceon the stator block during valve switching to reconfigure thecommunication of fluid flow paths coupled to the valve. In someexamples, multiple sample loops in the multi-valve array may used in aprocess to acquire sample slices from chromatographic peaks in theeluent of a first dimension chromatography system and subsequentlyintroduce the sample slices into a second dimension chromatographysystem. For example, multiple slices of a peak may be acquired if thereis a possibility that the sample composition across a peak is notconstant. In other examples, multiple sample loops within the blockhaving different volumes may be loaded with sample, potentiallyeliminating the need for partial loading of a sample loop having alarger volume.

FIGS. 1A and 1B show a top down view and a cutaway side view,respectively, of an embodiment of a stator body 10 having a first statorsurface 12 and a second stator surface 14. When assembled as a rotaryvalve array, each stator surface engages a rotor surface of acorresponding actuator portion of a rotary valve. In the figure, onlytwo stator ports 16 and 18 are indicated on each stator surface 12 and14, respectively. One set of stator ports 16A and 18A are provided atthe end of a fluid channel 20 that extends between the two statorsurfaces 12 and 14. The fluid channel 20 is shown as a dashed line inFIG. 1A as it is inside the stator body 10. The other stator ports 16Band 18B are at one end of fluid channels 22 and 24, respectively, whichterminate at their other ends at an external ports 26 and 28,respectively, at an external surface 30 of the stator body. The externalports 26 and 28 may be configured to couple to tubing or other form ofexternal channel using, for example, a fitting at an end of the tubing.Although the stator surfaces 12 and 14 are depicted as two regionsraised above the external surface 30, in other embodiments the externalsurface 30 may be at a similar or greater height as long as there is aseparation between the stator surfaces 12 and 14 from the neighboringregions of the external surface 30 so that the rotary valves may operateproperly and not interfere with each other. The minimum separationbetween the stator surfaces 12 and 14 may be limited according to thedimensions of the upper sections of the rotary valves which includes theactuator portions and rotors, and which are secured to the stator body10 using bolts or other attachment means.

In other embodiments, more complex fluid channel routing may be usedwith greater numbers of internal fluid channels and/or external ports onthe external surface of the stator body. In still other examples, theremay be greater numbers of stator surfaces to accommodate a greaternumber of rotary valves. In some embodiments, the fluid channels aremicrofluidic channels. For example, the fluid channels may have volumesof a few microliters or less.

The stator body 10 may be fabricated as a single plate using asolid-state diffusion bonding process in which two or more parallellayers of material are joined together. The layers are forced againsteach other under pressure at an elevated temperature (e.g., atemperature in a range of about 50% to 90% of the absolute melting pointof the material) for a duration ranging from a few minutes to severalhours). The pressure and temperature are then reduced before repeatingone or more additional cycles at the elevated temperature and pressure.Examples of materials used to create the diffusion-bonded stator bodyinclude titanium, stainless steel, and various types of ceramics andpolymers.

The diffusion bonding process may be performed where one or more of thelayers has a channel formed along a surface that will abut an adjacentsurface of a neighboring layer. These internal or “embedded” channels,along with vertical channels formed at their ends, define fluid channelsused to communicate fluids between the rotors and inlets and outlet onthe external surface 30 of the stator body 10. Depending on the numberof layers, a large number of fluid channels may be formed in the statorbody 10. In some embodiments, the fluid channels are defined betweendifferent layers at different depths so that some fluid channels maycross above or below other fluid channels to avoid interference and toallow for complex fluid channel configurations.

When performing two-dimensional chromatography using conventional rotaryvalves, external tubing is typically used for the sample loops. Eachtube requires a connection at each end to one of the rotary valves.Generally, it is desirable to have each sample loop hold the same volumeof liquid as the other sample loops. For small sample volumes, thelength of the tubing can be reduced; however, there is a fundamentallimit to reducing the length as the tubing is required to bridge betweenits coupling ports on the valve. The inner diameter (ID) of the tubingcan be reduced to achieve a smaller sample loop volume. However, due tothe manufacturing tolerance on the ID, the variations in volume for whatare intended to be equivalent volume sample loops becomes anincreasingly larger percentage of the desired sample loop volume withdecreasing ID.

Table 1 lists the nominal, minimum and maximum volumes associated withdifferent external sample loop IDs and lengths according to differentmanufacturing tolerances for the ID and length. It can be seen that thegreatest percentage variations in volume are associated with thesmallest sample loop volumes.

TABLE 1 ACQUITY HYPO SAMPLE LOOPS Hypo Sample Nominal Nominal MinimumMaximum Loop Size Nominal ID Length Volume Volume Volume (uL) (in)Tolerance+ Tolerance− (in) Tolerance+ Tolerance− (uL) (uL) (uL) 1 0.0040.0005 0.0005 5.00 0.03 0.03 1.03 0.78 1.31 2 0.004 0.0005 0.0005 9.750.03 0.03 2.01 1.53 2.55 5 0.007 0.0005 0.0005 7.95 0.03 0.03 5.01 4.315.78 10 0.010 0.0005 0.0005 7.79 0.03 0.03 10.03 9.01 11.10 ACQUITYSAMPLE LOOPS Sample Nominal Nominal Minimum Maximum Loop Size Nominal IDLength Volume Volume Volume (uL) (in) Tolerance+ Tolerance− (in)Tolerance+ Tolerance− (uL) (uL) (uL) 1 0.004 0.001 0.001 5.00 0.03 0.031.03 0.58 1.52 2 0.005 0.001 0.001 6.20 0.03 0.03 1.99 1.27 2.89 5 0.0070.001 0.001 7.93 0.03 0.03 5.00 3.66 6.56 10 0.012 0.001 0.001 5.40 0.030.03 10.01 8.36 11.81 10 - Bent 0.012 0.001 0.001 5.40 0.03 0.03 10.018.36 11.81 20 0.012 0.001 0.001 10.79 0.03 0.03 20.00 16.76 23.53 500.020 0.000 0.002 9.76 0.06 0.06 50.25 40.45 50.55 100 0.030 0.000 0.0028.63 0.06 0.06 99.96 86.47 100.66 250 0.030 0.000 0.002 21.59 0.06 0.06250.08 217.25 250.78

In contrast, Table 2 shows the nominal, minimum and maximum volumesassociated with different sample loops that can be formed in adiffusion-bonded body, such as the stator body 10 described with respectto FIGS. 1A and 1B. The smaller manufacturing tolerances for ID andlength result in significantly better control of the volume for smallsample loops. Thus, a diffusion-bonded stator body can have smallersample volumes than can be achieved with external sample loops whilehaving the additional advantage of more accurate volume control.

TABLE 2 DIFFUSION BONDED LOOPS Sample Nominal Nominal Minimum MaximumLoop Size Nominal ID Length Volume Volume Volume (uL) (in) Tolerance+Tolerance− (in) Tolerance+ Tolerance− (uL) (uL) (uL) 1 0.010 0.000050.00005 0.78 0.00005 0.00005 1.000 0.990 1.010 2 0.010 0.00005 0.000051.55 0.00005 0.00005 2.000 1.980 2.020 5 0.010 0.00005 0.00005 3.890.00005 0.00005 5.000 4.958 5.050 10 0.012 0.00005 0.00005 5.40 0.000050.00005 10.008 9.915 10.092 20 0.012 0.00005 0.00005 10.79 0.000050.00005 19.997 19.831 20.165 50 0.020 0.00005 0.00005 9.76 0.000050.00005 50.246 49.995 50.498 100 0.030 0.00005 0.00005 8.64 0.000050.00005 100.080 99.746 100.414

FIG. 2 shows a multi-valve array that is used to acquire samples from achromatography system in a first chromatographic dimension and tointroduce these samples into a second chromatography system of a secondchromatographic dimension. The configuration includes a first rotaryvalve 40 having eight fluid connections 40-1 to 40-8, a second rotaryvalve 42 associated with a first dimension chromatography system andhaving fourteen fluid connections 42-1 to 42-14, and a third rotaryvalve 44 associated with a second dimension chromatography system andhaving fourteen fluid connections 44-1 to 44-14.

The multi-valve array is shown in a state in which the system flow fromthe first dimension chromatography system is received at port 40-1 andexits through port 40-2 to the second valve 42. In this state, thesystem flow may contain a chromatographic peak such that the sample inthe peak is loaded into an external sample loop 43-1 that is the activeone of the six external sample loops 43-1 to 43-6. Alternatively, thesecond valve 42 may be switched so that only a portion of the sample inthe peak is loaded into the external sample loop 43-1 and so anotherportion of the sample in the peak may be loaded into a different sampleloop 43. Liquid displaced from the external sample loops 43 flows backto the first valve 40 at port 40-3 before exiting to waste through port40-4. The second valve 42 may be switched at different timescorresponding to the presence of the different chromatographic peaks sothat a series of samples from the peaks, or sample slices of anindividual peak, may be stored in the external sample loops 43.

The system flow of the second dimension upstream of the chromatographiccolumn is received at the first valve at port 40-5 and flow from port40-6 to the third valve 44 into one of six external sample loops 45-1 to45-6 that can hold sample for introduction into the second dimensionchromatography system. The system flow displaces the sample stored inthe external sample loop 45-1 that is part of the active flow pathaccording to the current state of the third valve 44. The displacedsample is received at port 40-7 of the first valve 40 and exits at port40-8 to flow to the chromatographic column of the second chromatographysystem. The third valve 44 may be switched to introduce another one ofthe stored samples from the other external sample loops 45 into thesecond chromatography system.

The multi-valve array may be operated in a complementary state byreconfiguring the state of the first valve 40 so that the roles of thesecond and third valves 42 and 44 are reversed from that shown in thefigure. In the complementary configuration, the system flow from thefirst dimension chromatography system is received at the third valve 44which is used to sample chromatographic peaks, or portions of peaks,from the first chromatography system. The system flow of the seconddimension is now managed by the second valve 42 which operates to injectsamples previously stored into its external sample loops 43 into theflow to the chromatographic column for the second dimension.

To accommodate the fluid paths in the illustrated multi-valve array,eight fluid connections are used for the first valve 40 and 14 fluidconnections are used for each of the second and third valves 42 and 44,for a total of 36 fluid connections. Typically, these connections aremade using compression screws and ferrules. The large number of fluidconnections results in a significant chance of leakage from at least onefluid connection.

FIG. 3A shows a top view of an example of a stator body 60 that can beused as part of a multi-valve array that replaces the multi-valve arraydepicted in FIG. 2. As referred to below with respect to the figures,the top side of the stator body 60 (and other stator bodies describedbelow) is the side which includes ports for coupling to externalconduits and the bottom side includes stator surfaces to engage rotorsurfaces of rotary valve actuators. FIG. 3B is a view of the stator body60 similar to that of FIG. 3A; however, the material is depicted astransparent so that internal fluid channels are visible. FIG. 3C is aperspective view of the transparent stator body 60 shown in FIG. 3B;however, the four layers 64-1 to 64-4 used in the diffusion bondingprocess are depicted. It should be recognized that the discrete layers64 are not distinguishable in the stator body 60 at the end of thediffusion bonding process. The description of the stator body 60provided below references all views presented in FIGS. 3A to 3C.

The stator body 60 includes four ports port 62-1 to 62-4 which arefunctionally similar to certain ports of the first rotary valve 40 shownin FIG. 2. Specifically, port 62-1 corresponds to port 40-1, port 62-2corresponds to port 40-4, port 62-3 corresponds to port 40-5 and port62-4 corresponds to port 40-8.

The stator body 60 includes three stator surfaces 66, 68 and 70 eachhaving multiple stator ports. The stator surfaces 66, 68 and 70 aredisposed on an opposite side (bottom side) of the body 60 form the fourports 62 as shown by the dashed circles in FIG. 3A. When used as part ofa two-dimensional chromatography system, one of the ports 62-1 is influid communication with the eluent from a chromatographic column in afirst dimension chromatography system and another port 62-2 is an outletport that is coupled to a waste fluid path. The third port 62-3 receivesa system flow of a second dimension chromatography system upstream ofthe second dimension chromatographic column and the fourth port 62-4 isan outlet port that provides the system flow to the inlet of the seconddimension chromatographic column.

Ports 62-1 to 62-4 are in fluid communication with the central statorsurface 66 through inlet or outlet fluid channels 72-1 to 72-4,respectively. The central stator surface 66 is also in fluidcommunication with stator surface 68 through fluid channels 74 and 76,and with stator surface 70 through fluid channels 78 and 80.

The stator body 60 includes two sets of internal sample channels. Oneset includes six sample channels 82-1 to 82-6 associated with statorsurface 68 and the other set includes six sample channels 84-1 to 84-6associated with stator surface 70. Each sample channel 82, 84 includestwo radial channel segments formed at a depth corresponding to theinterface of layers 64-1 and 64-2. A first end of each radial channelsegment is coupled, through a vertical channel segment, to acorresponding one of the stator surfaces 68 or 70. The second end ofeach radial channel segment is coupled, through a short vertical path,to one end of an arc-shaped channel segment (portion of acircumferential path). The arc-shaped channel segments are formed at adepth corresponding to the interface of layers 64-2 and 64-3. Thus, thefull path of a sample channel is defined by two radial channel segments,an arc-shaped channel segment, two vertical channel segments to the twoassociated stator ports and two additional vertical channel segmentsthat couple the arc-shaped segment to the two radial segments.

All the sample channels 82, 84 are machined to tight tolerances, forexample, as listed in Table 2. Consequently, the sample channels havebetter volume accuracy than conventional external sample loops. Each ofthe sample channels 82, 84 can be formed of channel segments having alength, width and depth that are accurately controlled so that eachsample channel can be made to have a volume that is substantially equalto the volumes of the other sample channels. As used herein with respectto volumes, “equal to” and “substantially equal to” means that thevolumes may differ, for example, due to manufacturing tolerances;however, such differences are sufficiently small so as to result innegligible differences in chromatographic measurements. The interchannelsample volume accuracy can be +/−1% which is an accuracy that cannot beachieved with external sample loops utilizing typicalcommercially-available tubing for plumbing liquid chromatographysystems. Consequently, for a sample that fully loads each of the samplechannels, the chromatographic measurement data are substantially thesame regardless of which sample channel is used for sample injection.

To avoid interference in terms of intersecting channels, the fluidchannels are formed at different interfaces of the four layers 64. Forexample, the lengths (i.e., non-vertical segments) of the fluid channels72, 74, 76, 78 and 80 may be formed at the interface of layers 64-3 and64-4. In alternative embodiments, the number of layers may differ. Forexample, for more complex multi-valve arrangements having additionalstator surfaces, sample channels and/or external ports, additionallayers may be used to accommodate a more complex fluid channel layout.Each fluid channel typically includes a short vertical segment at itends to connect it to a port on one of the stator surfaces or one of theexternal ports 62. In addition, each sample channel includes a verticalsegment that extends from one end of the arc-shaped segment through theintervening layer to one end of the radial segment. Vertical segmentscan be formed, for example, by drilling through one or more layersbefore diffusion bonding the layers together.

During operation, the system flow for the first dimension is received atport 62-1, flows through fluid channel 72-1 to the central statorsurface 66 and back out of the stator body 60 through fluid channel 72-2and port 62-2 to waste. The left valve is controlled such that the firstdimension system flow is directed to one of the sample channels 82 forloading with a sample (e.g., peak slice) as the sample is detected orotherwise known to be present in the first dimension system flow,otherwise the system flow exits to waste. The right valve is controlledsuch that the second dimension system flow through fluid channel 72-3 isdirected to one of the sample channels 84 to displace the containedsample into the system flow toward the second dimension chromatographiccolumn. Thus, the left and right valves can be operated to performsample loading for the first chromatographic dimension and sampleintroduction into the second chromatographic dimension, respectively.The center valve can be switched to change which set of sample channels82 or 84 is used for acquiring the first dimension samples and used forintroducing previously acquired first dimension samples into the seconddimension system flow.

In the embodiments described above with respect to FIGS. 3A to 3C, thereare six sample channels for each set. It should be recognized that inalternative embodiments, the number of sample channels per set can be asfew as one or any other number of sample channels that can beaccommodated by the physical size of the device and the layout of thefluid channels.

FIGS. 4A, 4B and 4C are a top view, transparent top view and transparenttop perspective view, respectively, of an example of a stator body 90that can be used as part of a multi-valve array for acquiring differentvolumes of sample for a chromatographic injection. Certain holes 92 and94 are not shown in FIGS. 4B and 4C to improve the clarity of theremaining features in the figures. FIG. 4D is an expanded view of thecentral portion of FIG. 4B and shows how various internal fluid channelsterminate at one of the stator ports 96-1 to 96-6. Also shown is ahybrid arc and serpentine layout to a fluid channel 98 that couplesstator ports 96-3 and 96-6.

As described above, the stator body 90 can be fabricated using adiffusion bonding process so that multiple fluid channels can be formedinside the body 90. By way of non-limiting examples of materials, thestator body 90 may be fabricated from one or more of titanium, stainlesssteel, and various types of ceramic materials and polymers.

The stator body 90 includes bolt holes 92 and alignment pin holes 94used to attach each of three rotary valve actuators and rotors to acorresponding stator surface. Six ports (ports 102-1 to 102-6) areprovided to conduct liquid to or from the stator body 90. Specifically,port 102-1 is at one end of a chromatography system inlet channel 103and is configured to receive a system flow (mobile phase) of achromatography system and port 102-2 is at one end of a chromatographysystem outlet channel 105 and is configured to provide an outlet for thesystem flow. Ports 102-3 and 102-4 are sample inlet and outlet ports,respectively, for a liquid flow containing a sample to be loaded intothree distinct sample channels. Ports 102-5 and 102-6 allow for couplingof an external sample loop to the stator body 90. In alternativeembodiments, there may be one or more additional ports to couple toadditional external sample loops or ports 102-5 and 102-6 may beomitted.

The plurality of internal fluid channels inside the stator body 90enables a multi-valve array to realize an improvement in performancerelative to a typical valve configuration that uses only external sampleloops. For example, unswept volumes corresponding to connectionsnecessary for external couplings are reduced and therefore carryover andcross-contamination are also reduced. The sample channels formed in thestator body 90 enable dimensional and volume accuracies that are notachievable with external sample loops. Consequently, multiple internalsample channels of different volumes can be used instead of resorting topartial filling of external sample loops because the volumes of theinternal sample channels and any external sample loops can cover alarger range of volumes than would be possible using partial sample loopfilling. Table 3 shows nominal, minimum and maximum volumes associatedwith 1.0 μl and 2.0 μl sample channels that can be formed in adiffusion-bonded body, such as the illustrated stator body 90. Thesmaller manufacturing tolerances for ID and length result insignificantly better control of the volume for small sample channels.Thus, a diffusion-bonded stator body can hold smaller sample volumesthan external sample loops while having the additional advantage of moreaccurate volume control. Regardless, the stator body 90 can still allowthe partial loop filing of an external sample loop (e.g., a sample loopconnected at ports 102-5 and 102-6) or a large volume internal samplechannel.

TABLE 3 ACQUITY SAMPLE LOOPS Sample Nominal Nominal Minimum Maximum LoopSize Nominal ID Length Volume Volume Volume (uL) (in) Tolerance+Tolerance− (in) Tolerance+ Tolerance− (uL) (uL) (uL) 1 0.008 0.000050.00005 1.22 0.001 0.001 1.0008 0.9875 1.0142 2 0.008 0.00005 0.000052.43 0.001 0.001 2.0016 1.9758 2.0275

The multi-valve array configured with the illustrated stator body 90 canbe used as a sampling interface between an extraction system and achromatographic system to perform an on-line extraction analysispermitting optimization of the extraction process. The array allows asample to be acquired at one time and stored in different volumes forsubsequent injections. As an extraction solvent passes through themulti-valve array, the extractant is sampled by directing it through oneor more of the internal sample channels, or the external sample loop,in-line with the chromatographic system. The ability to select differentvolumes associated with the internal sample channels and any externalsample loops can be used to address the amount of analytes in theextraction sample and the dynamic range of the chromatographic detector.More specifically, to quantitate or qualitatively compare analytesextracted from a sample, the signal from the chromatographic detectorshould be in a linear range of the detector. The multi-valve array canbe used to acquire sample into multiple internal sample channels andexternal sample loops of different volume. This allows an operator toselect the sample channel or loop having the appropriate volume togenerate a signal in the linear range of the detector. For example, if aprior sample injected from one of the sample channels or loop resultedin an “off scale” detector signal, the sample stored in a smaller volumeinternal sample channel or external loop can be injected. Alternatively,if the prior sample resulted in too small a detector response, thesample stored in a larger volume internal sample channel or externalloop can be injected.

The multi-valve array can be configured with different size samplechannels and loops to accommodate different application modes. By way ofnon-limiting examples, an array used for small molecule applications caninclude a 10 nL internal sample channel, a 100 nL internal samplechannel and a 1.0 μL external sample loop, and an array used for largemolecule applications can include a 1.0 μL external sample loop, a 5.0μL external sample loop and a 20.0 μL external sample loop.

FIG. 5A is a top view, transparent top view and transparent topperspective view, respectively, of an example of a stator body 100 thatcan be used as part of a multi-system injector array. The transparentviews show the body material as clear so that internal fluid channelsand features are apparent. Certain holes 102 and 104 are not shown inFIGS. 5B and 5C to improve the clarity of the remaining features in thefigures. FIG. 5D is an expanded view of the central portion of FIG. 5Band shows how internal fluid channels terminate at one of the statorports 106-1 to 106-6. A fluid channel 108 that couples stator ports106-3 and 106-6 has a serpentine arc shaped path.

The multi-system injector array can be used to acquire separate volumesof a sample for introduction into multiple chromatography systems. Forexample, the sample may be acquired from a process line and stored inthe separate volumes. This allows the sample to be analyzed by differentchromatography systems so that multi-attribute information (e.g.,information regarding the sample that cannot be obtained by a singlechromatography system) can be acquired.

The stator body 100 may be fabricated using a diffusion bonding processsuch as those described above. The stator body 100 includes bolt holes102 and alignment pin holes 104 used to attach each of three rotaryvalve actuators and rotors to a corresponding stator surface. The statorbody 100 includes ten external ports. Ports 112-1 and 112-2 are inletand outlet sample ports, respectively. Ports 112-3, 112-4 and 112-5 areinlet ports for receiving a system flow (mobile phase) from a firstchromatography system, a second chromatography system and a thirdchromatography system, respectively. Ports 112-6, 112-7 and 112-8 areoutlet ports for coupling to tubing that provides the system flows tothe chromatographic columns of the first, second and thirdchromatography systems. In alternative embodiments, there may be adifferent number of inlet and outlet ports according to the number ofchromatography systems used for analysis.

The stator body 100 includes a plurality of internal fluid channels thatprovide advantages similar to those for the above-described embodiments.In general, a single sample is loaded into multiple internal samplechannels and/or external sample loops in one continuous sequence. In theillustrated embodiment, the sample can be loaded into three storagevolumes: an external sample loop coupled to the stator body 100 at ports114-1 and 114-2, an internal sample channel 116 formed beneath thestator surface for the center valve, and an internal sample channel 118formed beneath the right stator surface. Once the sample is stored inthe external sample loop, the left rotary valve can be switched to astate in which the sample is injected into the mobile phase of the firstchromatography system. Similarly, once the samples are stored in theinternal sample channels 108 and 118, the center and right rotary valvescan be switched to states in which the samples are injected into themobile phases of the second and third chromatography systems,respectively.

FIGS. 6A and 6B are a top back view and a top front view, respectively,of an example of a multi-valve array 130 which includes a stator body132 such as those in the examples described above. The multi-valve array130 also includes three rotary shear seal valve pods 134 secured to thestator body 132 by bolts 136 which engage threaded holes 137 in a flange138 on each valve pod 134. In these and subsequent drawings, “A,” “B,”“C” and “D” used with reference numbers indicate the correspondence ofother illustrated components to valve pods 134A, 134B, 134C and 134D,respectively. Internal components of each valve pod 134, such as cloversprings, result in a force being applied to maintain each rotor surfaceagainst the corresponding stator surface on the stator body 132. Acomplete rotary shear seal valve includes a pod 132 and a valve drive(not shown). The valve drive has a rotatable drive shaft with features(e.g., alignment pins of different diameter) to engage, in a specificrotational orientation, a top end 139 of the pod 132 which is coupled toa pod shaft that rotates the rotor surface. The valve drive includes amotor and a gearbox mechanically coupled to the drive shaft.

In a conventional rotary shear seal valve, one or more screws or boltsare typically used to secure the valve pod to the valve drive tomaintain the valve drive in engagement with the valve pod. In theillustrated example, the stator body 132 does not permit the use ofscrews or bolts for this purpose because the associated through holes inthe stator body 132 could interfere with the internal fluid channels.

FIG. 7 shows a mounting assembly 150 that can be used with themulti-valve array to ensure proper engagement of the valve drives 152with the valve pods 134. The figure shows only two complete rotary shearseal valves so that various features of the mounting assembly 150 arevisible. A third valve pod 134C without a corresponding valve drive isshown attached to the stator body 132 and is visible to the right of theother two valve pods 134A and 134B. Unoccupied space for a fourth rotaryshear seal valve that is independent of the stator body 132 is visibleto the right of the third valve pod 134C.

The mounting assembly 150 includes a mounting frame having a front wall154, a back wall 156 opposite to the front wall 154, and four side walls158. The front wall 154 has four openings 159 (only one unoccupied) eachconfigured to pass a portion of one of the valve pods 134. The sidewalls 158 extend perpendicularly between the front wall 154 and the backwall 156. Each side wall 158 has a slot 160 that extends along a portionof its length between the front and back walls 154 and 156. In thefigure, the back wall 156 and side walls 158 are formed as a singleelement that is attached to a rack or tray 161 which includes the frontwall 154; however, in other examples, the walls 154, 156, 158 may beindividual wall structures or may be provided such that two or morewalls are integrally formed.

A spring element (not shown) is disposed on or against the insidesurface of the back wall 156 in a position opposite to one of theopenings in the front wall 154. By way of non-limiting examples, thespring element may be a compression spring or other force-applyingdeformable element such as a pneumatic, magnetic or electromagneticelement. When one of the valve locations in the mounting assembly 150 isoccupied by a valve pod 134 and valve drive 152, the spring element iscompressed between the back end of the valve drive 152 and the back wall156. The spring element urges the valve drive 152 forward, that is, in adirection away from the back wall 156 and toward the front wall 154which in turn maintains the valve drive 152 in engagement with therespective valve pod 132 and pushes the valve pod 132 forward toward thefront wall 154. A pair of guide screws (not shown) extending fromthreaded holes 162 on one of the sides of a valve drive 152 engages theslot 160 in an adjacent side wall 158. Only one slot 160 is used witheach valve drive 152. More specifically, valve drive 152A is used withthe slot in side wall 154A although side wall 154B is also adjacent.Valve drive 152B is used with the slot in sidewall 154B, and the slots160 in side walls 154C and 154D are available for two additional valvedrives (not shown). During assembly, each valve drive 152 issubstantially restricted by its slot 160 and engaged screws to movementin a direction parallel to the slot length, that is, in a directionparallel to the valve pod axes and valve drive axes. The screws may beshoulder screws. For example, each screw may have an unthreaded portionalong a length beneath the screw head where the screw passes through theslot 160 where the unthreaded length is greater that a thickness of theside wall 154. This configuration allows the valve drive 152 to movealong a linear path as it engages the valve pod 132. The slot 160 may bedimensioned such that its vertical dimension is greater than a diameterof the unthreaded portion of the screw by an amount that provides asmall vertical gap to allow easier engagement of the valve pod 132 tothe valve drive 152.

A retainer element 164 is used to secure the stator body 132 against thefront (external) surface of the front wall 154 while the spring elementis under compression. In some examples, the retainer element 164 is aflexible component that extends away from the front wall 154 and may bepushed downward. When released, the retainer element 164 moves towardits original position.

During assembly, the valve drives 152 are positioned in their properlocations adjacent the side walls 158 and the spring elements. Theretainer element 164 is pushed downward to allow the stator body 132with its attached valve pods 134 to be positioned so that a portion ofeach valve pod 134 extends through a corresponding opening 159 in thefront wall 154 and engages a valve drive 152. The retainer element 164is then released so that it moves toward its original position and comesin contact with the bottom surface 165 of the stator body 132. Theretainer element 164 applies force to the stator body 132 so that itstop surface 167 is in contact with the front wall 154 while the springelement forces the valve drive 152 to engage the valve pod 134. In thismanner, the stator body 132, valve drives 152 and valve pods 134 aresecurely held in their proper operating positions.

In one example, the retainer element 164 is a sprint clip formed of aresilient material and shown in more detail in the perspective, side andtop views provided in FIGS. 8A, 8B and 8C, respectively. The retainerelement 164 may be attached to the mounting assembly by two screws. Eachscrew passes through an elongate opening 166 and engages a threaded holeon the bottom side of the front wall 154. The retainer element 164 isadjusted by sliding in a direction along the length of the opening 166to a desired position before tightening the bolt. During installation,the front lip 168 is continually depressed downward to allow the statorbody 132 to pass and be placed in proper position against the front wall154. Once in place, the front lip 168 is released so that the retainerelement 164 returns to approximately its original shape and anengagement edge 170 comes into contact with and applied force to thefront surface of the stator body 132.

In alternative examples, the retainer element can take on any of a widevariety of other forms. The dimensions and shape of the retainer elementvary and are determined based on application of a desired force over acontact area. In other examples, two or more retainer elements are usedto apply force against the stator body 132 at multiple locations. Othermeans for applying a holding force to the stator body 132 may be used.For example, one or more toggle clips or friction devices may be used.Alternatively, a deformable material, such as a deformable polymer, maybe used.

The examples of mounting assemblies described above accommodate thevarious examples of stator bodies. Advantageously, the mounting assemblyprovides a quick and reliable means to secure a stator body so that theattached valve pods properly engage their valve drives without the needfor tools or any complicated alignment procedures. Similarly, removal ofthe stator body with its attached valve pods from the mounting assemblyis easily accomplished.

In alternative examples, various types of adaptors may be used with avalve drive and configured for use as described above. For example, avalve drive manufactured for use with a different type of valve pod maybe used with an adaptor to engage and properly register with theinternal components of the valve pod.

The arrangement of stator surfaces and valve pods is not limited tothose described above. In other alternative examples, the multi-valvearray may include a stator array that has stator surfaces for only twovalve pods or the stator array may have a number of stator surfacessufficient to allow attachment of four or more valve pods. Moreover, themulti-valve array may be a two-dimensional array. For example, the arraycan be an arrangement of two or more rows where each row includes two ormore valves. Alternatively, the stator body may be configured for othertwo-dimensional array configurations such as a triangular arrangement ofvalves.

Referring again to FIGS. 3B and 3C, it can be seen that an individualinternal sample channel 82, 84 in the stator body 60 includes anarc-shaped channel segment that extends 180° around its center ofcurvature and a radial channel segment extending from each end of thearc-shaped channel segment. The radial channel segments are formed atthe interface of layers 64-1 and 64-2 with the first end of each radialchannel segment coupled through an orthogonal (vertical) channel segmentto a corresponding one of the stator surfaces 68 or 70 and the secondend of each radial channel segment coupled through a short verticalfluid path to one end of the arc-shaped channel segment. The arc-shapedchannel segments are formed at the interface of layers 64-2 and 64-3.Although the full path length of each sample channel 82, 84 is definedby the lengths of the two radial channel segments, the arc-shapedchannel segment and the vertical channel segments, the total volume ofeach sample channel is determined primarily by the length of itsarc-shaped channel segment.

All twelve sample channels 82, 84 are intended to have the same volume,for example, 25 μL. Because the length of each arc-shaped channelsegment increases with increasing radius of curvature, arc-shapedchannel segments with larger radii of curvature have a correspondinggreater volume if the depths and widths of the arc-shaped channelsegments are the same.

FIG. 9A is a top cross-sectional view of the right-side portion of thestator body 60 (FIG. 3B) at the interface of layers 64-1 and 64-2 andFIG. 9B is a cross-sectional side view along the dashed line 85 show inFIG. 9A. Each sample channel 82 includes an arc-shaped channel segment86 with a radial channel segment 87, 88 coupling each end of thearc-shaped channel segment 86 to a short vertical channel leading to arespective port on the stator surface. Fluid channels 89-1 and 89-2conduct solvent and/or sample to or from a sample channel 82. Theparticular sample channel 82 coupled to the fluid channels 89 isdetermined by the valve state of the rotary valve.

The depth of each arc-shaped channel segment 86 below an externalsurface of the device is different from the depths of the otherarc-shaped channel segments 86. The channel segment 86-1 with thesmallest radius of curvature, defined as its distance from the center ofcurvature 83, has the greatest depth with each channel segment 86 ofgreater radius of curvature having a decreased depth such that thechannel segment 86-6 having the greatest radius of curvature has theleast depth. The depth is used as a controlled manufacturing variable toensure that all arc-shaped channel segments 82 have the same segmentvolume.

One disadvantage of the varying depth of the arc-shaped channel segments86 is that each channel segment 86 has a different flow characteristic.Generally, long channels having smaller diameters have lower dispersionas compared to shorter channels with larger diameters. Due to thedifferent lengths and depths of the channel segments 86, the dispersionfor each channel is generally different. Such differences lead tovariations in chromatographic measurements based on which sample channel82 is utilized.

FIG. 10A is a cross-sectional side view of a portion of a multi-channelfluidic device in the form of an alternative to the stator body 60 ofFIGS. 3A to 3C. The illustrated stator body 140 is formed from aplurality of layers 142 into a single body. Seven layers 142-1 to 142-7are diffusion bonded together to create the single body having multiplesample channels 144. Additional layers (not shown) may be provides andmay include openings to accept external fittings and to provide featuressuch as attachment features to facilitate attachment of the rotaryvalves. The layers 142 are parallel to each other and to one or moreexternal device surfaces.

Each sample channel 144 is disposed at a unique interface of two of thelayers 142. For example, sample channel 144-3 is formed at the interfaceof layers 142-3 and 142-4. Although the reference numbers 144-n (where nidentifies a particular sample channel) are associated with linesdirected to a single opening, it will be appreciated that all theopenings at that interface are part of the same sample channel. Theinterfaces are parallel to each other and to the external surfaces ofthe stator body 60. FIG. 10B shows a top cross-sectional view at theinterface of layers 142-3 and 142-4 of a larger portion of the statorbody 140 where the dashed line 146 indicates the location of thecross-sectional view of FIG. 10A. Thus, FIG. 10B shows only a singlesample channel 144-3.

Each sample channel 144 includes a hybrid serpentine arc (HAS)-shapedsegment 148 with a radial channel segment 151 coupling one end of theHAS-shaped segment 148 to a vertical channel segment that extends to aport on the stator surface 154. A second radial channel segment 152couples the other end of the HAS-shaped segment 148 to another port onthe stator surface 154 through another vertical channel segment. EachHAS-shaped segment 148 has the same shape but is oriented at a differentangular position with respect to a rotation about an axis 155. Forexample, the angular positions may be separated equally in angle by 60°.The illustrated HAS-shaped segment 148-3 is defined by a series ofcircumferential paths of less than 360° where, other than the innermostand outmost circumferential paths, each circumferential path is coupledto an adjacent path by a turning section 156. Each circumferential pathis defined by a radius of curvature that is different than the radii ofcurvature of the other circumferential paths. This geometricalarrangement of the HAS-shaped segment 148-3 allows for a significantvolume of sample to be stored. For example, the sample channels 144 mayeach have a volume of 250 μL.

An additional advantage to placing channels on individual loops is theability to have different channel segment volumes without changing thechannel segment geometries. In one non-limiting example, a single layerdefines a 250 μL channel segment and the device contains six layers.Therefore, six different volumes of 250 μL each can be accessed at 300rotations of the rotor. Pairs of layers can be serially connectedinternally to form three connected channel segments each containing atotal of 500 μL which can be accessed at 60° rotations of the rotor.Three layers can be combined to form two connected channel segmentscontaining a total of 750 μL, four layers can combined into a singleconnected group of channel segments containing a total of 1,000 μL, fivelayers can be combined into a single connected group of channel segmentscontaining a total of 1,250 μL, and six layers can be combined into asingle 1,500 μL connected group of channel segments. Thus, with minimalchanges to the interconnect geometry, the valve can supportconfiguration flexibility.

The sample channel 144-3 may be coupled to other regions (e.g., featuresor ports) of the stator body 140 through fluid channels 158 and 160 whenthe rotary valve is in a particular valve state. Other sample channels144 present at the interface of other layers 142 may be coupled throughfluid channels 158 and 160 by reconfiguring the valve state of therotary valve.

Advantageously, by providing each HAS-shaped channel segment 148 at adifferent layer interface in the stator body 140, the volumes of thesample channels 144 can be made nearly identical. The differences in thevolumes of the vertical channel segments for each sample channel maylead to a small variation in the sample channel volumes; however, thesedifferences can be on the order of 0.1% or less.

Sample channel path geometries other than those described above arecontemplated. For example, the HAS-shaped channel segments 148 may bereplaced with a differently shaped channel segment as long as the shapeavoids interference between the channel segments that extend out of theplane of the interfaces of the layers and so that the volumes of thesample channels are substantially similar. In this context, substantialsimilarity of volumes means that the usefulness of a chromatographicmeasurement made with the device is unaffected by which sample channelis employed for the measurement.

In the various embodiments described above the number of internal samplechannels or external sample loops that may be accessed by a singlerotary valve is limited according to the number of valve ports. Forexample, rotary valves 42 and 44 in FIG. 2 allow for six sample channelsto be coupled to either valve; however, there are no means for fluid topass through either valve while bypassing the sample channels 43 and 45,respectively, unless one of the sample channels is instead tasked to bea bypass channel, leaving only the five other sample channels to holdsample. Moreover, the delay volume of such a bypass channel can addsignificant time to operations due to the transit time of fluid throughthe channel, especially for larger sample channel volumes and lower flowrates.

FIGS. 11A to 11H are diagrams depicting the configuration of a rotorwith respect to a stator for eight different rotor positions of a rotaryvalve. In these diagrams, the rotary valve includes a diffusion-bondedstator body having a stator surface that abuts a rotor surface of asingle rotary valve actuator. In alternative embodiments, the statorbody may be formed using a different fabrication technique. For example,a three-dimensional (3D) printing process can be used to create internalchannels at multiple layers inside a stator body.

The stator surface includes an inlet port 202, an outlet port 206 andtwelve additional ports 208 disposed along a circle concentric with acenter of rotation of the abutting rotor surface. These additionaltwelve ports 208 are referred to herein as “selectable ports” as theparticular ports that are in fluidic communication with the inlet port202 or outlet port 206 are determined by the valve state, that is, therotary position of the rotor. The twelve selectable ports 208 areequally spaced in angle with respect to the rotor rotation axis. Thestator body also includes internal fluidic channels 210 (only the endsof the channels visible) with each channel providing a fluidic pathbetween a pair of diametrically-opposed selectable ports 208, asdescribed in more detail below. In some alternative embodiments,external tubing is used instead of internal fluidic channels to providethe fluidic paths between the selectable ports 208.

During operation, an inlet channel 200 conducts fluid to the inlet port202 and an outlet channel 204 conducts fluid from the outlet port 206.The inlet and outlet channels 200 and 204 may be formed in a sameinterface layer or in different interface layers of the diffusion-bondedstator body. Vertical channel segments at the opposite ends of the inletand outlet channels 200 and 204 lead to coupling fixtures at an externalsurface of the diffusion-bonded stator body that enable externalconduits to be fluidically coupled to the rotary valve. The slight bendsin the inlet and outlet channels 200 and 204 are provided to avoidinterference with certain vertical channels in the stator body.

Six internal sample channels 210-1 to 210-6 are formed in thediffusion-bonded body with each channel 210 configured to hold a sample.The volumes of the sample channels 210 may be defined according to aparticular application. In a non-limiting numerical example, the volumeof each sample channel 210 is 250 μL. In some applications, the rotaryvalve can be operated so that the volume of a stored sample may be lessthan the full volume of the sample channel 210.

In some embodiments, each sample channel 210 is formed at the sameinterface layer, similar to the configuration shown in FIGS. 9A and 9B.In other embodiments, such as those described below, each sample channel210 is formed at a separate interface layer, similar to theconfiguration shown in FIGS. 10A and 10B. A vertical channel segmentpassing through one or more layers of the diffusion-bonded body may beused to conduct fluid into or out from a sample channel 210 to acorresponding stator port 208. The volume of these vertical channels issmall compared to the volumes of the sample channels 210 such that anyvariation in volume between the sample channels due to different lengthsof their vertical channel segments is negligible.

FIG. 12 shows a magnified view of the twelve selectable ports 208 andfeatures on the rotor surface corresponding to the rotor position shownin FIG. 11A. Two rotor channels 212 and 214 are formed on the rotorsurface, for example, as grooves having specific geometries. The firstrotor channel 212 has a compound shape that includes an arc portion212-1 and a linear portion 212-2. The arc portion 212-1 is defined at aradius R₁ from the rotor rotation axis such that it remains incommunication with the inlet port 202 over a range of rotor positions asshown in FIGS. 11A to 11F, i.e., across approximately 150° of rotorposition. The linear portion 212-2 extends radially from one end of thearc portion 212-1 and enables the channel 212 to be fluidically coupledto any of the selectable ports 208. The second rotor channel 214 isdefined by an arc portion 214-1 and a short linear portion 214-2 at oneend farthest from the rotor rotation axis. The other end of the secondrotor channel 214 is disposed on the rotor rotation axis. The radialdistance R₂ from the rotor rotation axis to the end of the linearportion 214-2 corresponds to a radius of the circle on which the twelveselectable ports 208 are disposed. As the rotor rotates, the end of thesecond rotor channel 214 disposed on the rotor rotation axis remains influidic communication with the outlet port 206 while the other endrotates to enable fluidic coupling to one of the selectable ports 208.

Referring again to FIGS. 11A to 11F, the six rotor positions depicted inthe six figures are separated in angle with respect to the rotorrotation axis such that incrementing the rotor position by integermultiples of 30°, clockwise or counterclockwise within an angular rangeof approximately 0° to 180° results in a change in the valve state toallow any of the other sample channels to be coupled between the inputand output valve ports 202 and 206. By way of a non-limiting example, anaccuracy of rotor positioning of 1.0° can accommodate switching to anyof the six rotor positions. For example, FIG. 11A shows a valve state inwhich a solvent flow from inlet channel 200 flows through the inlet port202, first rotor channel 212, selectable port 208-7, sample channel210-1, selectable port 208-1, second rotor channel 214, outlet port 206and exits the stator body through outlet channel 204. In another valvestate in which the rotor is incremented in position through 30°, asshown in FIG. 11B, a solvent flow from inlet channel 200 flows throughthe inlet port 202, first rotor channel 212, selectable port 208-8,sample channel 210-2, selectable port 208-2, second rotor channel 214,outlet port 206 and exits the stator body through outlet channel 204.Four other valve states, as shown in FIGS. 11C to 11F, result insimilarly directing the solvent flow through one of the four othersample channels 210-3 to 210-6.

FIGS. 11G and 11H show two additional rotor positions at which therotary valve operates in a bypass state such that fluid received at theinlet port 202 passes to the outlet port 206 without having to passthrough any of the sample channels 210. In FIG. 11G, the rotor positionis 195° and most of the inlet port 202 overlaps the arc portion 214-1 ofthe second rotor channel 214. As the rotor rotates to a rotor positionof 200°, as shown in FIG. 11H, the inlet port 202 is entirely “within”the arc portion 214-1; however, the linear portion 212-2 of the firstrotor channel 212 has moved to almost reach a stator port 208-2. Thus,an appropriate bypass state can be associated with an angular range ofrotor position or at a fixed position with the angular range. Forexample, the bypass position may be defined approximately midway betweenan angular ranged defined by the two illustrated rotor positions, forexample, at a rotor position of approximately 197°.

It can be seen that when the rotary valve is in a bypass state, thefluid path length between the inlet port 202 and the outlet port 206 isonly a portion of the arc length of the arc portion 214-1 of the secondrotor channel 214. Thus, the delay volume through the rotary valve issmall, especially in comparison to the large delay volume resulting fromsacrificing one of the sample channels 210 for use as a bypass channel.

In various embodiments described above, the rotary valve includes twelveselectable ports, an inlet port and an outlet port. It will beappreciated that a rotary valve having a similar bypass state caninclude a fewer or greater number of ports. For example, the geometriesof the first and second rotor channels 212 and 214 may be different toaccommodate a particular number and arrangement of ports at the statorsurface.

While various examples have been shown and described, the description isintended to be exemplary, rather than limiting and it should beunderstood by those of ordinary skill in the art that various changes inform and detail may be made therein without departing from the scope ofthe invention as recited in the accompanying claims.

The invention claimed is:
 1. A rotary valve, comprising: a statorcomprising a stator surface having an inlet port, an outlet port, and aplurality of selectable ports; a plurality of sample channels eachcoupling one of the selectable ports to another one of the selectableports; and a rotor comprising a rotor surface in abutment with thestator surface, the rotor surface having a first rotor channel and asecond rotor channel defined therein, the rotor having a plurality ofrotor positions at which the first rotor channel couples the inlet portto one of the selectable ports at one end of one of the sample channelsand the second rotor channel couples the outlet port to another one ofthe selectable ports that is at an opposite end of the one of the samplechannels, the rotor having a bypass rotor position at which the inletport is coupled to the outlet port through the second rotor channel andthe first rotor channel is not coupled to the inlet port, not coupled tothe outlet port and not coupled to any of the selectable ports.
 2. Therotary valve of claim 1 wherein, for each sample channel, the selectableports coupled at the end of each sample channel are diametricallyopposite to each other on the stator surface with respect to a rotorrotation axis.
 3. The rotary valve of claim 2 wherein the selectableports are disposed at equally spaced angular positions with respect tothe rotor rotation axis.
 4. The rotary valve of claim 1 wherein thebypass rotor position is defined within an angular range with respect toa rotor rotation axis.
 5. The rotary valve of claim 1 wherein the outletport is disposed along a rotor rotation axis.
 6. The rotary valve ofclaim 1 wherein the first rotor channel includes an arc portion having acenter of curvature on a rotor rotation axis.
 7. The rotary valve ofclaim 1 wherein the stator surface is defined on a diffusion-bonded bodyand wherein the sample channels are defined by internal channels in thediffusion-bonded body.
 8. The rotary valve of claim 7 wherein theinternal channels are defined in different layers of thediffusion-bonded body.
 9. The rotary valve of claim 1 wherein eachsample channel comprises tubing.
 10. The rotary valve of claim 1 whereinthe second rotor channel defines a fluidic path from a rotor rotationaxis to a position on a circle on which the selectable stator ports aredisposed, the circle being concentric with the rotor rotation axis. 11.The rotary valve of claim 10 wherein the second rotor channel comprisesan arc portion and a linear portion, the arc portion having a first endat the rotor rotation axis and a second end, the linear portionextending from the second end to the circle.
 12. The rotary valve ofclaim 10 wherein the second rotor channel comprises a plurality oflinear portions.